Neurodegenerative disorders afflict numerous patients throughout the world and can be devastating to patients and caregivers. Such disorders also can result in great financial burdens, with annual costs currently exceeding several hundred billion dollars in the United States alone. Current treatments for such disorders often are inadequate. Further, many such disorders are age-related, and thus their incidence is rapidly increasing as demographics trend toward an aging population. For example, glaucoma, a disease, disorder, or condition that results in damage to the optic nerve, is a major cause of vision loss and blindness, especially in the elderly. Although various treatments for glaucoma exist, many such treatments are of limited efficacy and/or have significant side effects. Reduction of intraocular pressure, generally through pharmacologic or surgical intervention, is presently the mainstay of glaucoma therapy. Such therapies, however, often are only partially effective and generally cannot restore neuronal cell function once such function has been lost.